Belfast weather in August 2025

Q: How hot is it in Belfast in August?

Daytime temperatures usually reach 18°C in Belfast in August, falling to 11°C at night.

Q: How sunny is it in Belfast in August?

There are normally 5 hours of bright sunshine each day in Belfast in August - that's 32% of daylight hours.

Q: How warm is the sea around Belfast in August?

The average sea temperature around Belfast in August is 13°C.

Q: Does it rain in Belfast in August?

There are usually 17 days with some rain in Belfast in August and the average monthly rainfall is 89mm.

Expect daytime maximum temperatures of 18°C in Belfast, Northern Ireland in August based on long-term weather averages. There are 5 hours of sunshine per day on average with 17 days with some rainfall and typically 89 mm of rainfall in the month.

18
18°C max day temperature
5
5 hours of sunshine per day
17
17 days with some rainfall
11
11°C min night temperature
15
15 hours of daylight per day
0
No heat & humidity
89
89 mm of monthly rainfall
5
5 (Moderate) UV index
13
13°C sea temperature

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The August weather guide for Northern Ireland (Belfast) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm) | Imperial (°F / inches)